Fluidic control system of fuel injection device for internal combustion engines

ABSTRACT

A control system for a fuel injection device of internal combustion engine, which comprises trigger pulse generator for generating a trigger pulse in synchronism with the rotation of an internal combustion engine, a variable circuit-length device by which the length of a fluid passage can be varied according to the load on the engine and a fluidic control circuit for generating a fluidic pulse of a variable width in cooperation with said variable circuit-length device, and in which the trigger pulse generated by said trigger pulse generator is applied to the fluidic control circuit and said variable circuitlength device, whereby a fluidic pulse is generated by said fluidic control circuit and the fluidic pulse thus generated is used for controlling the quantity of fuel supplied to the engine.

[54] FLUIDIC CONTROL SYSTEM OF FUEL INJECTION DEVICE FOR INTERNALCOMBUSTION ENGINES Inventors: Kazuma Matsui, Toyohashi; Hideo Tsubouchi,Kariya, both of Japan Assignee: Nippondenso Kabushiki Kaisha,

Kariya-shi, Aichi-ken, Japan Filed: March 30, 1971 Appl. 190.; 129,544

[30] Foreign Application Priority Data US. Cl.....123/119 R, 123/103 R,123/139 AW,

123/DIG. 10, 261/DIG. 69

Int. Cl. ..F02n 37/14, Fl5c l/00, F02d 11/08 Field of Search ..123/119R, 103 R, 139 AW,

DIG. l0; 261/DIG. 69

. generator for [451 Sept. 12, 1972 [56] References Cited UNITED STATESPATENTS 3,556,063 l/l97l Tuzson ..l23/103 R 3,585,975 6/1971 Tonegawa etal...l23/DIG. 10 3,616,782 ll/l97l Matsui et al. ..123/1l9 R PrimaryExaminer-Wendell E Bums AttorneyCushman, Darby & Cushman [57] ABSTRACT Acontrol system for a fuel injection device of internal combustionengine, which comprises trigger pulse generating a trigger pulse insynchronism with the rotation of an internal combustion engine, avariable circuit-length device by which the length of a fluid passagecan be varied according to the load on the engine and a fluidic controlcircuit for generating a fluidic pulse of a variable width incooperation with said variable circuit-length device, and in which thetrigger pulse generated by said trigger pulse generator is applied tothe fluidic control circuit and said variable circuit-length device,whereby a fluidic pulse is generated by said fluidic control circuit andthe fluidic pulse thus generated is used for controlling the quantity offuel supplied to the engine.

7 Claims, 25 Drawing Figures PATENTED l 2 I972 3.690. 306 sum 01' or 11PATENTEDsmzmz 3.690.306

SHEET 02 0F 11 'fu(mm sec) F I 4 t 760 (mm Hg) 660 (mm Hg Max" MinPATENTED 12 I972 3.690.306

SHEET USUF 11 F l G. 6

PATENTEDsEP 12 I972 SHEET GBUF 11 340a 34le PATENTEMEHZIBIZ 3.690.306sum over 11 PKTENTED 3.690.306

sum user 11 FIG. 9

Tb (mm sec) I Max Min"

360 56o 76o 'ro oo P2 (mm Hg) FIG.|O

L g g Q 5 g 300 500 700 760 800 -P3 (mm Hg) PKTENTEU 3.690.306

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360 56o 76o vo oo P4 (mm Hg) 0 F G. l5

t 0 760 (mm Hg) 660 (mm Hg) Min FLUIDIC CONTROL SYSTEM OF FUEL INJECTIONDEVICE FOR INTERNAL COMBUSTION ENGINES This invention relates to acontrol system for a fuel injection device of internal combustionengines which injects fuel directly into the suction manifold of theengine while atomizing the fuel without using a carburetor.

As a fuel injection device of internal combustion engines, there hasbeen used a suction type carburetor which utilizes the vacuum pressureat the Venturi portion in the suction pipe of an engine,a mechanicalinjection device which injects fuel directly into each cylinder orsuction manifold of an engine without using a carbureter of the typedescribed, or an electrical injection device which has electronic meansat a fuel controlling portion thereof.

The suction type carbureter mentioned above sucks and discharges fuel bymaking use of a pressure lowering of the suction gas at a fixed Venturior variable Venturi. The fixed Venturi type carbureter, as is wellknown, has the disadvantage that systems for a low speed operation, anintermediate speed operation and a high speed operation must inevitablybe separated from each other according to the velocity range of thesuction gas flow and a smooth operation of the engine is impaired at thepoint when the carburetor is connected to each system. On the otherhand, the variable Venturi type carburetor can eliminate theabove-described disadvantage of the fixed Venturi type, but has thedisadvantage that mechanisms for operatively associating a variablefluidic resistance provided in the fuel passage with the variableVenturi, and said variable Venturi with the flow rate of air sucked intothe engine, etc., not only call for a precision in machining but alsobecome complicated in construction and large in size, and thustheproduction cost thereof becomes high.

The mechanical and electronic injection devices are also complicated inconstruction and high in production cost, and therefore, are rarely usedfor internal combustion engines other than those which are used forspecial applications.

The first object of the present invention is to provide a control systemwhich controls a fuel injection device of internal combustion engines insuch a manner that an adequate quantity of fuel as demanded by theengine can be supplied to the engine continuously from a low speedoperation to a high speed operation of the enme. g The second object ofthe invention is to provide a control system which is simple inconstruction, easy to manufacture and capable of operating the fuelinjection device of the internal combustion engine with high accuracy.

The third object of the invention is to provide a control system whichcontrols the fuel injection device in such a manner that, in a highspeed, high load region of the engine, fuel is injected continuouslyexcept for a very short period of time corresponding to the pulseinterval, and as a result, enables the capacity of a pump to be reducedwhich delivers the fuel to fuel injecting portions with pressure.

The fourth object of the invention is to provide a control system whichcontrols the fuel injection device in such a manner that an optimumquantity of fuel which has been compensated according to an atmosphericpressure change, is supplied to the engine.

The fifth object of the invention is to provide a control system for thefuel injection device, which comprises a multi-element as a fluidiccontrol circuit and an electrically operated compressor as a source ofcompressed air for said element, and the function of which will not beimpaired even if compressed air is supplied during stoppage of theengine.

According to the present invention, there is provided a control systemfor a fuel injection device of internal combustion engines, whichcomprises trigger pulse generating means for generating a trigger pulsein synchronism with the rotation of an internal combustion engine,variable circuit-length means by which the length of a fluid passage canbe varied according to the load on said engine and fluidic controlcircuit for generating a fluidic pulse of a variable width and avariable number in cooperation with said variable circuitlength meansand said trigger pulse generating means, the trigger pulse generated bysaid trigger pulse generating means being applied to said fluidiccontrol circuit and said variable circuit-length means, whereby afluidic pulse is generated by said fluidic control circuit, which isused for controlling the quantity of fuel supplied to said engine.

FIG. 1 is a diagram showing, partially in section and partiallyschematically, a first embodiment of the control system according to theinvention as applied to an internal combustion engine;

FIG. 2 is a longitudinal cross-sectional view showing in an enlargedscale the variable circuit-length (fluid flow) device shown in FIG. 1;

FIGS. 3a through 3f are diagrams showing the waveforms of pulsesgenerated at various portions of the control systems in the firstthrough fourth embodiment, respectively;

FIG. 4 is a diagram showing the relationship between the pressure in thesuction manifold of the internal combustion engine and the delay time ofthe pulses, under different atmospheric pressures, in the first throughfourth embodiment;

FIG. 5 is a view showing, partially in section and partiallyschematically, the second embodiment of the control system according tothe invention as applied to an internal combustion engine;

FIG. 6 is a view showing, partially in section and partiallyschematically, the third embodiment of the control system according tothe invention as applied to an internal combustion engine;

FIG. 7 is a view showing, partially in section and partiallyschematically, the fourth embodiment of the control system according tothe invention as applied to an internal combustion engine;

FIG. 8 is a transverse cross-sectional view of the variablecircuit-length device of the fourth embodiment;

FIG. 9 is a diagram showing the relationship between the absolutepressure in the suction manifold of the intemal combustion engine andthe pulse delay time in the fourth embodiment;

FIG. 10 is a diagram showing the relationship between the absolutepressure in the suction manifold of the internal combustion engine andthe quantity of fuel to be supplied to the engine for each revolutionthereof, in the fourth embodiment;

FIG. 11 is a view showing, partially in section and partiallyschematically, a fifth embodiment of the control system according to theinvention as applied to an internal combustion engine;

FIG. 12 is a transverse cross-sectional view of the variablecircuit-length device for the compensation of the atmospheric pressure,in the fifth embodiment;

FIGS. 13a through 13f are diagrams showing the waveforms of pulsesgenerated at various portions of the control system in the fifthembodiment, respectivey;

FIG. 14 is a diagram showing the relationship between the absoluteatmospheric pressure and the pulse delay time when the plunger of thevariable circuit-length device moves, in the fifth embodiment; and

FIG. '15 is a diagram showing the relationship between the absolutepressure in the suction manifold of the internal combustion engine andthe quantity of fuel to be supplied to the engine for each revolutionthereof, under different atmospheric pressures, in the fifth embodiment.

The present invention will be described on five embodiments thereofsequentially as applied to an internal combustion engine mounted on avehicle, such as an automotive vehicle, with reference to theaccompanying drawings:

.FIGS. 1 and 2 show the first embodiment of the present invention. Inthese figures, reference numeral 1 designates a compressed air pumpdriven from an internal combustion engine or electric motor; 2 anairpressure regulating valve by which the pressure of the air dischargedfrom the compressed air pump 1 is maintained constant; 3 a fluidiccontrol circuit; 4 a fluidic multivibrator element consisting of afluidic flip-flop element; 4a the power supply port of said element; 4b,4c the control ports of said element; and 4d, 42 the output ports ofsaid element. Reference numeral designates a variable circuit-lengthdevice and 5a designates a cylinder of said variable circuit-lengthdevice which has a helical groove 5b and an elongate groove 50 formedindependently in the inner surface thereof. Reference numeral 5ddesignates a power supply port communicating with one end of saidhelical groove Sb-and also with the output port 4d of the multivibratorelement 4. The pitch of the helical groove 5b is made smaller at the endportion remote from the power supply port 5d. Reference numeral 5edesignates an output port of the variable circuit-length device 5, whichcommunicates with said elongate groove 50 and also with the control port4b of the multivibrator element 4. Reference numeral 5f designates aplunger axially slidably disposed in the cylinder 5a; 5g an annular portformed in the peripheral surface of the plunger 5f at a portion opposedby the helical groove 5b; 5h a port formed in the peripheral surface ofsaid plunger 5f at a portion opposed by the elongate groove 50; and Si apassage formed in said plunger 5f and communicating said ports 5g, 5hwith each other. Reference numeral Sj designates a power cylinder formedaxially of the cylinder 5a integrally therewith and 5k designates adiaphragm disposed in said power cylinder 5j and dividing the interiorof said power cylinder into a negative pressure chamber 5e and anatmospheric pressure chamber 5m. The negative pressure chamber Se iscommunicated with the suction manifold of the engine through a negativepressure introducing pipe 5n for introducing the manifold vacuumpressure thereinto, while the atmospheric pressure chamber 5m iscommunicated with the atmosphere through a communication port 50. Thediaphragm 5k and the plunger 5f are connected with each other by a bolt5p. Further, the diaphragm Skis urged toward the atmospheric pressurechamber 5m by a spring Sq disposed in the negative pressure chamber Se.Reference numerals 6a, 6b, 6c, 6d each designate a fixed fluidicresistance consisting, for example, of an orifice. Reference numeral 7designates a fluidic monostable multivibrator element having a powersupply port 70, a control port 7b and output ports 7c, 7d. The outputport is communicated with the control port 40 of the multivibratorelement 4 and the other output port 7d is opened into the atmosphere.Reference numeral 7' designates another fluidic monostable multivibratorhaving a power supply port 7a, a control port 7b and output ports 7'c,7'd. The output port 7'c is communicated with a compressed air nozzle 25to be described later. The arrangement is such that when a signal fromthe output port 4e of the multivibrator element 4 is applied to thecontrol port 7b of the monostable multivibrator element 7, a signalequivalent to a signal generated at the output port 4d of saidmultivibrator element 4 is amplified and appears at the output port 7'cof the monostable multivibrator element 7'. At the output port 7d isgenerated a signal of a phase exactly reverse to that of the signalgenerated at the output port 7'c but this signal is released into theatmosphere. Reference numeral 8 designates a fluidic detector fordetecting the rate -of rotation of the engine 9,which generates an airpulse signal synchronized with the rotation of said engine. The detector8 includes a rotary body 10 and a member 11 abutting against said rotarybody 10. The rotary body 10' rotates at the same rate as that, forexample, of the cam shaft of the internal combustion engine 9 and makesone revolution on two revolutions of the crank shaft. Further, therotary body 10 has circumferential grooves 11c, 11d formed at portionsof the peripheral surface thereof and generates one pulse Pa, as shownin FIG. 3a on every revolution of the crank shaft. The member 11 has apower supply port 11a and an output port 11b formed therein toward theperipheral surface of the rotary body 10. The output port 11b iscommunicated with the control port 7b of the monostable multivibratorelement 7. The detector 8 generates one output air pulse at its outputport 1 lb only when the communication between the power supply port 11aand the output port 11b is established by each of the grooves 11c, 11dof the rotary body 10, and therefore, generates two air trigger pulsesin each revolution of said rotary body 10. The compressed air pump 1 andthe air pressure regulating valve 2 supply a constant pressure ofcompressed air to each of the power supply port 4a of the multivibratorelement 4, the power supply ports 7a, 7'a of the monostablemultivibrator elements 7, 7 and the power supply port 11a of thedetector 8, and the pressure ratio of the compressed air supplied tosaid respective ports is adjusted by the fixed fluid resistances 6a, 6b,6c.

Reference character A generally indicates the internal combustion engine9 and devices associated with said engine, such as a fuel tank 29, afloat chamber 28,

etc., which will be described hereunder: Reference numeral 14 designatesa cylinder of the engine 9, 15 a piston, 16 an intake valve, and 17 anexhaust valve. Reference numeral 18 designates an intake passagecommunicating with the intake valve 16, 19 a suction manifold connectedto the intake passage 18, and 20 a throttle valve provided in thedownstream side of the suction manifold 19. Reference character 1generally indicates a fuel injecting portion, in which reference numeral21 designates a hood of a fuel injection chamber, 22 the fuel injectionchamber, 23 a fuel injection nozzle projecting into said chamber 22, and24 a tubular fuel receiving pipe projecting into the chamber 22. Thefuel injection nozzle 23 and the fuel receiving pipe 24 are arranged inopposed relation to each other with a certain distance therebetween andsubstantially axially aligned with each other. Reference numeral 25designates a compressed air nozzle projecting into the fuel injectionchamber 22, with the axis thereof extending at right angles to a lineconnecting the tip ends of the fuel injection nozzle 23 and the fuelreceiving pipe 24. A fuel return passage 26 has one end connected to thefuel receiving pipe 24, with the other end leading into the floatchamber 28. Reference numeral 29 designates a fuel tank and 30designates a pump by which fuel F in said fuel tank 29 is supplied intosaid float chamber 28 with pressure, 31 a fuel injection pump and 31a abattery constituting a power source for said pump 31. Reference numeral32 designates a pressure regulating valve by which the dischargepressure of the pump 31 is maintained constant. The fuel F in the floatchamber 28 is set to the fuel injection nozzle 23 at a predeterminedpressure and a predetermined flow rate by the pressure regulating valve32 and the fuel injection pump 31. Reference numerals 33a, 33b designatecam shafts to open and close the intake valve 16 and exhaust valve 17respectively. Reference numeral 34 designates a negative pressuresensing port opened into the suction manifold 19 at a point downstreamof the throttle valve 20 and communicating with the negative pressureintroducing pipe 5n of the variable circuit-length device 5. The plunger5f of the variable circuit-length device 5 and the throttle valve 20operatively connected by a link mechanism 35 through a switching device42 which operates on a special occasion, so that said plunger 5f may beoperated on the special occasion according to the degree of opening ofsaid throttle valve 20. The output port 7'c of the multivibrator element7 is communicated with the compressed air nozzle 25. Reference numeral36 designates a valve which senses an abrupt deceleration of the engineby way of the manifold vacuum pressure from the negative pressuresensing port 34 and interrupts the air pulse signal supplied from thedetector 8 to the control port 7b of the monostable multivibratorelement 7. Reference numeral 37 designates a valve which detects amalfunction of the compressed air pump 1 by way of presence or absenceof the discharge pressure of said pump and interrupt the power supply tothe fuel injection pump 31. Reference numeral 38 designates a checkvalve and 39 designates an air injection nozzle positioned with its axisextending toward the exhaust valve 17 and communicating with thedischarge side of the compressed air pump 1. Reference numeral 13designates an ignition switch of the vehicle and the fuel injection pump31 is set in motion when said ignition switch 13 is closed.

The control system of the invention constructed as described aboveoperates in the following manner: Namely, a constant pressure ofcompressed air is always supplied to the power supply port 4a of themultivibrator element 4, the power supply ports 7a, 7'a of themonostable multivibrator elements 7, 7' and the power supply port 11a ofthe rate of rotation detector 8 by the compressed air pump 1 and the airpressure regulating valve 2. When the air pulse signal Pa as shown inFIG. 3a, generated at the output port 11b of the detector 8 is appliedto the control port 7b of the monostable multivibrator element 7 undersuch condition, said element 7 generates an air pulse of a width m, asshown in FIG. 3b, irrespective of the rate of rotation of the engine 9.The air pulse thus generated at the output port 7c is applied as atrigger signal to the control port 40 of the next stage multivibratorelement 4, whereupon the compressed air entering the power supply port4a of said element 4 is directed into the output port 4d and the outputfrom said output port 4d is partially supplied to the power supply port5d of the variable circuit-length device 5. The compressed air thusintroduced into the variable circuit-length device 5 passes at the sonicvelocity through a passage formed by the helical groove 5b, the annularport 5b, the passage 5i, the port 5h and the elongate groove 50, andreaches the output port 5e, with a time delay as determined by thelength of said passage. Since the length of the passage Si ispredetermined, the delay time is varied by the length of the helicalgroove 5b from the power supply port 5d to the annular port 5g(hereinafter referred to as effective length). The plunger 5f constantlymoves according to the magnitude of the manifold vacuum pressureintroduced into the negative pressure chamber 5e, and further moves onthe special occasion according to the degree of opening of the throttlevalve transmitted thereto through the link mechanism 35. Now, when themanifold vacuum pressure is introduced into the negative pressurechamber 5e through the negative pressure sensing port 34 and thenegative pressure introducing pipe 5n, the diaphragm Skis attractedtoward the negative pressure chamber 56 under the effect of negativepressure against the biasing force of the spring Sq, and accordingly theplunger 5f is moved in the direction of the arrow B,. The amount ofmovement of the plunger 5 f is proportional to the magnitude of thenegative pressure introduced into the negative pressure chamber 5e. Uponmovement of the plunger 5f in the direction of the arrow 8,, the annularport 5g is brought into communication with the helical groove 5b. Thus,it will be understood that the effective length of the passage becomesprogressively short and hence the delay time becomes progressivelysmall, as the negative pressure in the negative pressure chamber 5ebecomes large. On the contrary, the effective length of the passage and,therefore, the delay time becomes progressively long as the negativepressure in the negative pressure chamber 5e decreases. The sameoperation as described above takes place also in the event when theplunger 5f is moved by the link mechanism 35. The relationship betweenthe pressure P (mml-Ig) in the suction manifold 19 and the delay time ta(mm sec) of the curve indicated by reference character E represents thecharacteristic of the control system when the engine is operated on thehorizontal ground where the atmospheric pressure is 760 mrnI-Ig. Thepitch of the helical groove 5b is made small at the end remote from thepower supply port 5d so that the gradient of curve E may be relativelygentle within the range of the pressure in the manifold 19 from 400 to700 mmI-Ig but may be relatively sharp when the pressure exceeds 700mmI-Ig. A curve indicated by reference character D represents thecharacteristic of the control system when the engine is operated on thehigh ground, such as in the mountains, where the atmospheric pressure is660 mmI-Ig. As seen, the curve D is the curve E which is displaced tothe left parallel to the axis of abscissa by a distance corresponding to100 mmI-Ig. Reference symbol Max on the axis of ordinate indicates thepoint where the delay time of the pulse is longest, and Min indicatesthe point where the delay time is shortest. With the rate of rotation ofthe engine being constant, when pulses (each of a width of m,) delayed,for example, by times 1,, t t as shown in FIG. 3c, by the variablecircuit-length device 5, are applied to the control port 4b of themonostable multivibrator element 4, the flow of compressed air which hasbeen passing through the output port 4d, is directed into the outputport 4e. When the pulse applied to the control port 4b is P shown inFIG. 3c, a compressed air pulse of Pd, shown in FIG. 3d is generated atthe output port 4d. Similarly, when the pulse is P0 a compressed airpulse of Pe shown in FIG. 3e, and when the pulse is P0 a compressed airpulse of Pf shown in FIG. 3f, is generated at the output port 4d. Thewaveform of each pulse is rectangular and the period thereof is t Thewidths of the respective compressed air pulses Pd Pe Pf are determinedby the delay time provided by the variable circuit-length device 5,i.e., the magnitude of the manifold vacuum pressure representing thesize of the engine load, and are indicated by t t 1 respectively.

In order to follow the high speed operation of the engine,-it isnecessary to increase the quantity of fuel supplied during one cycle ofoperation of the engine to the possible extent, by reducing the pulseinterval and increasing the pulse width, even though the period of thepulse is short. If an arrangement is made such that a pulse Pc isgenerated when the delay time provided by the variable circuit-lengthdevice 5 is t and longest, as shown in FIG. 3f, and the falling point ofthis pulse becomes equal to the rising point of the output compressedair pulse Pb of the monostable multivibrator element 7, the pulseinterval will become shortest and m, and the pulse width will becomelargest and t The sum of the maximum value t of pulse width and theminimum value m of pulse interval is the period of the pulse and thisperiod is determined by the maximum rate of rotation of the engine.Therefore, the time which can be used for injecting the fuel can be madelongest, even during the high speed operation of the engme.

At the output port 4e are generated compressed air pulses whose phasesare reverse to those of the blown pulses generated at the output port 4dand shown in FIGS. 3d, 3e, 3f, respectively. When the compressed airpulses generated at the output port 4e are applied to the control port7b of the monostable multivibrator element 7', amplified compressed airpulses of the same phases as those of the pulses shown in FIGS. 3d, 3e,3f are generated at the output port 7 '0 respectively.

Where no compressed air pulses are generated at the output port 7c ofthe multivibrator element 7, a jet of fuel injection nozzle 23 flowsentirely into the fuel receiving pipe 24 and returned to the floatchamber 28 through the fuel return passage 26.

However, when a compressed air pulse appears at the output port 7c ofthe multivibrator element 7', said compressed air pulse is jetted fromthe compressed air nozzle 25, so that the fuel passing from the fuelinjection nozzle 23 into the fuel receiving pipe 24 is deflected andatomized into the suction manifold 19 and the atomized fuel is injectedinto the cylinder 14 through the throttle valve 20. In order to obtain asuction gas of a predetermined fuel air ratio, it is only necessary tocontrol the ratio between the product of the suction efficiency and theair density (which is proportional to the quantity of air sucked in.each cycle of the engine 9) and the pulse width, to be a predeterminedvalue. In the present invention, the fuel air ratio is constantlycontrolled to be an optimum value by varying the quantity of fuel to beinjected, according to the magnitude of the manifold vacuum pressuresupplied into the negative pressure chamber 5e of the variablecircuit-length device 5 through the negative pressure sensing port 34and according to the degree of opening of the throttle valve 20 on aspecial occasion.

On the other hand, the compressed air from the compressed air pump 1 issupplied to the air injecting nozzle 39 through the check valve 38 andinjected from said nozzle toward the exhaust valve 17. Therefore, thetoxic gases, such as carbon monoxide and unburned hydrocarbons,contained in the exhaust gas are oxidized and rendered harmless whichthey are exhausted through the exhaust valve 17.

In decelerating the engine 9 quickly, the valve 36 is actuated tointerrupt the air pulse supplied from the rate of rotation detector 8 tothe control port 7b of the monostable multivibrator element 7.Therefore, the air flowing into the power supply port 4a of themultivibrator element 4 continuously discharged from the output port 4e,as no air pulses are supplied to the control port 40. Consequently, nooutput pulse signals are generated at the output port 7 'c of themonostable multivibrator element 7 and the fuel injected from the fuelinjection nozzle 23 is entirely received in the fuel receiving pipe 24to be returned to the float chamber 28. In other words, when the engine9 is to be quickly decelerated, the fuel supply to the engine is stoppedand the discharge of the exhaust gas is also stopped.

When the compressed air pump 1 fails, the compressed air pulse is nolonger supplied to the compressed air nozzle 25 and therefore, the fuelinjected from the fuel injection nozzle 23 is entirely received in thefuel receiving pipe 24 and returned to the float chamber 28. In thiscase, the fuel is continuously circulated and the fuel vapor is releasedinto the atmosphere during circulation, which is not only dangerous butalso causes pollution of the atmosphere. According to the invention,however, the valve 37 is actuated upon failure of the compressed airpump 1, to interrupt the current supply to the fuel injection pump 31and thereby interrupt the fuel supply to the fuel injection nozzle 23.

In this embodiment, the signal generated at the output port 4d of thefluidic monostable multivibrator element 4 is amplified by the fluidicmonostable multivibrator element 7' and the amplified signal of the samephase is obtained at the output port 7'c of said element 7', asdescribed above. However, it should be understood that the output port4d of said element 4 may be communicated directly with the air injectionnozzle 25 to be described later, without providing the element 7'0, andin this case, the waveform of the pulse reaching the injection nozzle 25unavoidably becomes deformed and weakened to some extent.

in the first embodiment of the control system according to the presentinvention which is constructed as described above, the output signal ofthe fluidic monostable multivibrator circuit passing through the feedback circuit is delayed by a time corresponding to the engine load, byvarying the length of the helical passage according to the engine loadand then applied to the control port of said monostable multivibratorelement. The monostable multivibrator element performs its functiondepending upon whether the delayed output signal has arrived at thecontrol port or not, and generates a compressed air pulse having a widthcorresponding to the engine load; In this way, it is possible to supplya quantity of fuel just enough to meet the demand of the enginecontinuously from a low speed operation to-a high speed operation of theengine according to the rate of rotation of said engine Further, thefluidic monostable multivibrator circuit operates depending upon whetherthe output signal delayed by the variable circuit-length device hasarrived at the control port thereof. Therefore, the multistableoperation is highly accurate and fast and the width of the output pulseof the fluidic monostable multivibrator circuit, i.e., the quantity offuel injected can closely follow the engine load. Another excellentadvantage is that a fluctuation of the pulse width can be avoided evenif the monostable multivibrator circuit is designed with a certaindegree of freedom. Furthermore, according to the instant invention thecontrol system operates highly reliably and the entire system can beprovided in a compact form, because the injection of fuel does notdirectly involve a mechanical moving part and none of the partsassociating with the fuel injection particularly call for machiningprecision, and in addition, the fluidic elements are small in size andcan be put together at one location, no additional works being requiredother than piping. Therefore, the control system of the invention ishighly adapted for use with an internal comoustion engine of anautomobile wherein the available space is particularly limited, makes itpossible to prolong the useful life of the engine and can be provided ata low cost.

It should also be noted that, in the present invention, the minimumvalue of pulse interval of the output compressed air pulse signal of thesecond fluidic monostable multivibrator element can be reduced to avalue equal to the pulse width of the output pulse of the first fluidicmonostable multivibrator element. Therefore, by previously setting theoutput pulse of the first fluidic monostable multivibrator element at asmall value, it is possible to make the aforesaid pulse interval verysmall and thereby to inject a quantity of fuel demanded by the engine,into the suction manifold continuously and uniformly, not only in thelow speed, low load region but also the high speed, high load region ofthe engine, except for a very short period of time corresponding to thepulse interval. This is very advantageous in that a fuel injection pumpof small capacity can be used at the fuel injecting portion and in thatthe quantity of fuel supplied to the respective cylinders of amulti-cylinder engine can be uniformalized.

The second embodiment of the invention will be described hereunder withreference to FIG. 5 in which same parts or devices as those used in thefirst embodiment are indicated by same reference numerals with addedthereto. In FIG. 5, reference numeral 101 designates a compressed airpump driven from an internal combustion engine or an electric motor, 102an air regulating valve by which the discharge air pressure of saidcompressed air pump 101 is maintained constant; 103 a fluidic controlcircuit; and 104 a fluidic monostable multivibrator element having apower supply port 104a, control ports 104b, 104e, 104a, an OR outputport 104d and a NOR output port 104e. The output port 104d and thecontrol port 1040 are communicated with each other by a pipe l04f forpositive feed back, and the output port l04e is opened into the atmosphere. Reference numeral 105 designates a variable circuit-lengthdevice which is identical in construction with the variablecircuit-length device 5 shown in FIG. 1. A power supply port 105d of thedevice 105 is communicated with a pipe communicating an output port 107cof a fluidic monostable multivibrator element 107 to be described laterand the control port 104a of the monostable multivibrator element 104with each other, and an output port 105e thereof is communicated withthe control port 104b of said element 104. Reference numerals 106a,106b, 106e, 106d designate fixed fluidic resistances, each consisting,for example, of an orifice, respectively. Reference numeral 107designates a fluidic monostable multivibrator element having a powersupply port 107a, a control port 107b and output ports 107e, 107d. Theoutput port 107c is communicated with the control port 1046 of themonostable multivibrator element 4 and the other output port 107d isopened into the atmosphere. Reference numeral 108 designates a fluidicrate of rotation detector which generates an air pulse in synchronismwith the rotation of the engine 109. The detector 108 is identical inconstruction with the detector 8 shown in FIG. 1 and is designed togenerate one pulse Pa shown in FIG. 3a on every revolution of the crankshaft. An output port lllb of a member 111 is communicated with thecontrol port 107b of the monostable multivibrator element 107. Thecompressed air pump 101 and the air pressure regulating valve 102 supplya constant pressure of compressed air to each of the power supply ports104a, 107a of the monostable multivibrator elements 104, 107 and thepower supply port 111a of the detector 108, and the pressure ratio ofthe compressed air supplied to said respective ports is adjusted by thefixed fluidic resistances 106a, 106b, 1060.

Reference character A generally indicates the internal combustion engine109 and devices associated therewith, and the construction of theportion A is exactly identical with that of A, in FIG. 1. A compressedair nozzle 125 is communicated with the OR output port 104d of themonostable multivibrator element 104, and a negative pressure sensingport 134 is communicated with a negative pressure introducing pipe 105nof the variable circuit-length device 105. A plunger. 105f of thevariable circuit-length device 105 and a throttle valve 120 areoperatively connected with each other by a link mechanism 135 through aswitching device 142 which is operated on a special occasion, so thatsaid plunger lf may be operated on a special occasion according to thedegree of opening of said throttle valve 120. The functions of valves136, 137 are exactly the same as those of the valves 36, 37 in FIG. 1.

The second embodiment of the invention constructed as described aboveoperates as follows: A constant pressure of compressed air is alwayssupplied to the power supply ports 104a, 107a of the monostablemultivibrator elements 104, 107 and the power supply port 1 1 1a of thedetector 8 by the compressed air pump I01 and the air pressureregulating valve 102. When the air pulse signal Pa shown in FIG. 3a andgenerated at the output port lllb of the detector 108 on everyrevolution of the crank shaft is applied to the control port l07b of themonostable multivibrator element 107 as a trigger pulse, under suchcondition, said element 107 generates the air pulse Pb, of a pulse widthtn, as shown in FIG. 3b, at its output port 1070 irrespectively of therate of rotation of the engine 109. The air pulse generated at theoutput port 1070 is partially supplied as a trigger pulse to the controlport 1040 of the next stage monostable multivibrator element 104,whereby the compressed air which has been flowing from the power supplyport 104a into the NOR output port 104e, is directed into the OR outputport 104d. The compressed air discharged from the OR output port 104d ispartially supplied to the control port 1040 after restricting the flowrate by the fluidic resistance 106d. By so doing, the compressed aircontinues to flow through the OR output port 104d, even after thecompressed air pulse supplied from the output port 1070 of themonostable multivibrator element 107 to the control port 1040 of themonostable multivibrator element 104 disappears. On the other hand, thecompressed air pulse generated at the output port 1070 of the monostablemultivibrator element 107 is partially supplied to the power supply port105d of the variable circuitlength device 105. The compressed air pulsethus supplied passes at the sonic velocity through the passage formed bya helical groove 105b, an annular port 105g, a passage 105i, a port l05hand an elongate groove 1050, and reaches the output port 1050 with adelay time as determined by the length of said passage. Since the lengthof the passage 105i is predetermined, the delay time is varied by thelength of the helical groove l05b from the power supply port 105d to theannular port 105g (hereinafter referred to as effective length). Theeffective length of the variable circuit-length device 105 is varied inthe following manner: Namely, the plunger l05f constantly movesaccording to the magnitude of the manifold vacuum pressure introducedinto a negative pressure chamber 151, and further moves on a specialoccasion according to the degree of opening of the throttle valve whichis transmitted through the link mechanism 135. Now, when the manifoldvacuum pressure is introduced into the negative pressure chamber 151through the negative pressure sensing port 134 and the negative pressureintroducing pipe n, a diaphragm 105k is attracted under suction towardthe negative pressure chamber 151 against the biasing force of a spring105q and accordingly the plunger l05f is also moved in the direction ofthe arrow B The amount of movement of the plunger 105f is proportionalto the magnitude of the negative pressure introduced into the negativepressure chamber 151. Upon movement of the plunger 105f in the directionof the arrow 8,, the annular port 105g is shifted to a position tocommunicate with the helical groove 105b. Thus, it will be understoodthat the aforesaid effective length and hence the delay time becomesprogressive short as the negative pressure in thenegative pressurechamber 151 becomes progressively large, and conversely becomesprogressively long as the latter becomes progressively small. Theabovedescribed operation similarly takes place when the plunger l05f ismoved by the link mechanism 135. The relationship between the pressure P(mml-lg) in the suction manifold 119 and the pulse delay time ta (mmsec) is exactly the same as described previously with reference to thefirst embodiment and as shown in FIG. 4. With the rate of rotation ofthe engine being constant, when the pulses (each of a width of tndelayed, for example, by times t,, t t by the variable circuitlengthdevice 105 as shown, for example, in FIG. 30, are applied to the controlport 104b of the monostable multivibrator element 104, the compressedair flow which has been passing through the OR output port 104d, isdirected into the NOR output port 1040. Therefore, if the pulse appliedto thecontrol port 104b is P0 shown in FIG. 30, a compressed air pulseof Pd shown in FIG. 3d is generated at the output port 104d, andsimilarly, if the pulse is P0 or P0 a compressed air pulse of P0 or Pfshown in FIG. 30 or 3f appears at said port respectively. The widths ofthe pulses Pd Pe Pf, are the values of t t t which are determined by thedelay times provided by the variable circuit-length device 105 or themagnitude of the manifold vacuum pressure representing the size of theengine load, respectively.

In order to follow the high speed operation of the engine, it isnecessary to increase the quantity of fuel supplied during one cycle ofoperation of the engine to the possible extent, by reducing the pulseinterval and increasing the pulse width, even though the period of thepulse is short. If an arrangement is made such that a pulse P0 isgenerated when the delay time provided by the variable circuit-lengthdevice 105 is t and longest, as shown in FIG. 3f, and the falling pointof this pulse becomes equal to the rising point of the output compressedair pulse Pb, of the monostable multivibrator element 107, the pulseinterval will become shortest and m,, and the pulse width will becomelargest and The sum of the maximum value t: of pulse width and theminimum value tn of pulse interval is the period of the pulse and thisperiod is determined by the maximum rate of rotation of the engine.Therefore, the time which can be used for injecting the fuel can be madelongest, even during the high speed operation of the engine.

At the output port 104e is generated a compressed air pulse of a phasereverse to the air pulse generated at the OR output port 104d but saidcompressed air pulse is released into the atmosphere.

However, when no compressed air pulses are generated at the OR outputport 104d of the monostable multivibrator element 104, the fuel injectedfrom a fuel injection nozzle 123 in the form of a jet flows entirelyinto a fuel receiving pipe 124 to be returned to a float chamber 128through a fuel return passage 126.

Now, when a compressed air pulse is generated at the output port 104d ofthe monostable multivibrator element 104, said compressed air pulse isjetted from a compressed air nozzle 125, so that the fuel passing fromthe fuel injection nozzle 123 into the fuel receiving pipe 124 isdeflected and atomized by said compressed air pulse and injected intothe suction manifold 1 19 to be injected into a cylinder 1 14 through athrottle valve 120. In order to obtain a mixture of a desired fuel airratio, it is only necessary to control the ratio between the product ofthe suction efficiency and the air density (which is proportional to thequantity of air sucked into the engine for each cycle of the engine),and the pulse width, to be a certain value. In this embodiment, the fuelair ratio is controlled to be an optimum value at all times, by varyingthe quantity of fuel to be injected in accordance with the magnitude ofthe manifold vacuum pressure introduced into the negative pressurechamber 151 of the variable circuit-length device 105 through thenegative pressure sensing port 134, as described above.

As stated above, the rate of rotation detector 108 generates two of thepulse Pa shown in FIG. 3a during two revolutions of the crank shaft orone cycle of the engine. Therefore, two compressed air pulses aregenerated at the OR output port 104d of the monostable multivibratorelement 104 in each cycle of the engine based on the pulse Pa and thewidth of said pulse corresponds to the size of the engine load.Particularly in the high speed, high load region of the engine, thewaveform of the compressed air pulse generated at the OR output port104d becomes close to the waveform shown in FIG. 3f, the pulse widthbecomes extremely wide and the pulse interval becomes extremely close tothe value of m Namely, the fuel injected from the fuel injection nozzle123 for one cycle of engine is almost entirely injected into the suctionmanifold 119 continuously by the compressed air pulse of an extremelywide width jetted from the compressed air nozzle, except for a shortperiod of time corresponding to the pulse interval, and a very smallquantity of fuel injected from the fuel injection nozzle 123 during saidshort period of time only is returned to the float chamber 128 throughthe fuel receiving pipe 124. Particularly, in the high speed, high loadregion of the engine, a quantity of fuel demanded by the, engine for onecycle of operation can be continuously uniformly injected into thesuction manifold 119 during the period of one cycle, except for theaforesaid very short period of time. This makes it possible to use apump of smaller capacity for a fuel injection pump 131 than the capacityof the pump required in the case when a quantity of fuel demanded by theengine is injected all at once for only a short period of time duringone cycle of the engine. In addition, where the engine is amulti-cylinder engine, the

quantities of fuel to be supplied to the respective cylinders can beuniforrnalized. These advantages are particularly apparent in thehighspeed, high load region of the engine. Moreover, in the low speed, lowload region of the engine, the fuel injection period can be shortened totn, by shortening the pulse delay time to tn, and thereby the quantityof fuel to be injected can be minimized.

In this embodiment also, the toxic gases in the exhaust gas are oxidizedand rendered harmless by the compressed air blown from an air injectionnozzle 139 through a check valve 138; the fuel supply to the engine 109is interrupted at the time of abrupt deceleration of the engine, by theoperation of the valve 136; and the current supply to the fuel injectionpump 131 is interrupted by the operation of the valve 137 upon failureof the compressed air pump 101, to interrupt the fuel supply to the fuelinjection nozzle 123, as described previously with reference to thefirst embodiment.

In this embodiment, the power supply port d of the variablecircuit-length device 105 is communicated with the pipe whichcommunicates the output port l07c of the monostable multivibratorelement 107 and the control port- 104c of the monostable multivibratorelement 104 with each other, as stated above, but said power supply port105d may be communicated directly with the output port 104d of saidelement 104.

Because of the construction described above, the second embodiment ofthe control system has the same effects as those of the first embodimentdescribed previously.

An additional advantage of this embodiment is that, since the compressedair pulse generated at the OR output port of the second monostablemultivibrator element is supplied to the fuel injecting portion, even ifan electrically operated compressor is used for supplying compressed airto said second multivibrator element and compressed air is continuouslysupplied to said power supply port during the period when the engine isnot operated, such compressed air flows into the NOR output port and notinto the OR output port, and therefore, gives no detrimental effect onthe system at all.

The third embodiment of the invention will be described hereunder withreference to FIG. 6 wherein same members or devices as those of thefirst embodiment shown in FIG. 1 are indicated by the same referencenumerals with 200 added thereto, respectively. In FIG. 6, referencenumeral 201 designates a compressed air pump driven from an internalcombustion engine mounted on a vehicle; 202 an air regulating valve bywhich the discharge air pressure of said compressed air pump 201 ismaintained constant; 203 a fluidic control circuit; and 204 a fluidicbistable multivibrator element consisting of a fluidic flip'flot elementand having a power supply port 204a, control ports 204b, 2040, andoutput ports 204d, 2041:. One of the output port 204e is opened into theatmosphere. Reference numeral 205 designates a variable circuitlengthdevice which is identical in construction with the variablecircuit-length device 5 shown in FIG. 1. An input port 205d of thevariable circuit-length device 205 is communicated with a pipe whichcommunicates an output port 207a of a fluidic monostable multivibratorelement 207 to be described later and the control port of the bistablemultivibrator element 204 with each other, and an output port 205ethereof is communicated with the control port 204b of said element 204.Reference numerals 206a, 206b, 206e, 206d designate fixed fluidicresistances each consisting, for example, of an orifice. Referencenumeral 207 designates a fluidic monostable multivibrator element havinga power supply port 207a, a control port 207b and output ports 207c,207d. The output port 2070 is communicated with the control port 2040 ofthe multivibrator element 204 and the other output port 207d is openedinto the atmosphere. Reference numeral 208 designates a fluidic rate ofrotation detector which generates an air pulse signal in synchronismwith the rotation of the engine and is of exactly the same constructionas the detector 8 shown in FIG. 1. Namely, the detector 208 generatesone pulse Pa shown in FIG. 3a on every revolution of the crank shaft. Anoutput port 211b of a member 211 is communicated with the control port207b of the monostable multivibrator element 207.

A predetermined pressure of compressed air is supplied by the compressedair pump 201 and the air pressure regulating valve 202 to each of thepower supply port 204a of the bistable multivibrator element 204, thepower supply port 207a of the monostable multivibrator element 207 and apower supply port 211a of the detector 208, and the ratio of thecompressed air pressure supplied to said respective ports is adjusted bythe fixed fluidic resistances 206a, 206b, 2060, 206d.

Reference character A generally indicates the engine 209 and devicesassociated therewith, and the construction of the portion A, is exactlythe same as that of A shown in FIG. 1. A compressed air nozzle 225 iscommunicated with the output port 204d of the bistable multivibratorelement 204, and a negative pressure sensing port 234 is communicatedwith a negative pressure introducting port 205n of the variablecircuitlength device 205.

A plunger'205f of the variable circuit-length device 205 and a throttlevalve 220 are operatively connected by a link mechanism 235 through aswitching device 242 which is operated on a special occasion, so thatsaid plunger 205f is moved on a special occasion in accordance with thedegree of opening of said throttle valve 220. The functions of valves236, 237 are same as those of the valves 36, 37 shown in FIG. 1.

Now, the operation of this embodiment of the invention will bedescribed. As stated, a predetermined pressure of compressed air isconstantly supplied to each of the power supply port 204a of thebistable multivibrator element 204, the power supply port 207a of themonostable multivibrator element 207 and the power supply port 211a ofthe rate of rotation detector 208 from the compressed air pump 201 andthe air pressure regulating valve 202. When the air pulse signal Pashown in FIG. 3a and generated at the output port 21 lb of the detector208 on every revolution of the crank shaft is applied to the controlport 20711 of the monostable multivibrator element 207 as a triggerpulse under such condition, an air pulse Pb, of a width tn as shown inFIG. 3b is generated at the output port 2070 of said element 207irrespectively of the rate of rotation of the engine. The air pulse thusgenerated at the output port 207c is applied as a trigger pulse to thecontrol port 204a of the bistable multivibrator element 207, whereuponthe compressed air flow passing through the power supply port 204a ofsaid bistable multivibrator element 207 is directed into the output port204d. The air pulse supplied to the control port 2040 is partiallysupplied to a power supply port 205d of the variable circuit-lengthdevice 205. The air pulse thus supplied passes at the sonic velocitythrough a passage formed by a helical groove 205b, an annular port 205g,a passage 205i, a port 205k and an elongate groove 205s, and reaches anoutput port 205e with a time delay as determined by the length of saidpassage. Since the length of the passage 205i is predetermined, thedelay time is varied by the length of the helical groove 205b from thepower supply port 205d to the annular port 205g (hereinafter referred toas effective length). The plunger 205f constantly moves according to themagnitude of the manifold vacuum pressure introduced into a negativepressure chamber 251, and further moves on a special occasion accordingto the degree of opening of the throttle valve transmitted theretothrough the link mechanism 235. Now, when the manifold vacuum pressureis introduced into the negative pressure chamber 251 through thenegative pressure sensing port 234 and the negative pressure introducingport 205n, a diaphragm 205k is attracted toward said negative pressurechamber 251 by the effect of vacuum pressure against the biasing forceof a spring 205q, and'accordingly the plunger 205f moves in thedirection of the arrow B The amount of movement of the plunger 205f isproportional to the magnitude of the negative pressure introduced intothe negative pressure chamber 251. Upon movement of the plunger 205f inthe direction of the arrow B the annular port 205g is displaced to aposition to communicate with the helical groove 205b. Therefore, theaforesaid effective length and hence the delay time becomesprogressively short as the negative pressure in the negative pressurechamber 251 increases, and conversely becomes progressively long as thelatter decreases. The same operation as described above takes place alsowhen the plunger 205f is moved by the link mechanism 235. Therelationship between the pressure P (mmHg) in the suction manifold 219and the pulse delay time is as shown in FIG. 4 and exactly the same aspreviously described with reference to the first embodiment.

With the rate of rotation of the engine being constant, when the pulsesdelayed by the variable circuit- Iength device 205, for example, bytimes 2 t as shown, for example, in FIG. 3c (the width of the pulsesbeing all tn are applied to the control port 204b of the bistablemultivibrator element 204, the compressed air flow which has beenflowing into the output port 204d, is directed into the output port204e. Therefore, if the pulse applied to the control 204b is Pc shown inFIG. 30, a compressed air pulse of Pd, shown in FIG. 3d is generated atsaid output port 204e. Similarly, if the pulse is Pc or P0 a compressedair pulse of Pe or Pf shown in FIGS. 3e or 3f respectively is generatedat said output port 204e, and the widths of said respective pulses Pd PePf are the values of t t t respectively which are determined by thedelay time provided by the variable circuit-length device 205 or themanifold vacuum pressure representative of the size of the en gine load.

1. A control system for a fuel injection device of internal combustionengines, comprising trigger pulse generating means for generating atrigger pulse in synchronism with the rotation of an internal combustionengine, variable circuit-length means by which the length of a fluidpassage can be varied according to the load on said engine and fluidiccontrol circuit for generating a fluidic pulse of a variable width and avariable number in cooperation with said variable circuit-length meansand said trigger pulse generating means, the trigger pulse generated bysaid trigger pulse generating means being applied to said fluidiccontrol circuit and said variable circuit-length means, whereby afluidic pulse is generated by said fluidic control circuit, which isused for controlling the quantity of fuel supplied to said engine.
 2. Acontrol system for a fuel injection device of internal combustionengines, according to claim 1, wherein said fluidic control circuitincludes a multivibrator element, and said variable circuit-length meansis inserted in a negative feed back circuit of said element or in acircuit by which a pipe for applying the trigger pulse to a firstcontrol port of said element therethrough communicates with a secondcontrol port of said element.
 3. A control system for a fuel injectiondevice of internal combustion engines, according to claim 2, whereinsaid trigger pulse generating means includes a rate of rotationdetecting unit adapted to generate a pulse by intermittentlyinterrupting a fluid passage and a monostable multivibrator element forshaping the output pulse of said rate of rotation detecting unit.
 4. Acontrol system for a fuel injection device of internal combustionengines, according to claim 3, wherein said monostable multivibratorelement included in the trigger pulse generating means is a one-shotmonostable multivibrator element and said multivibrator element includedin the fluidic control circuit is a bistable multivibrator element.
 5. Acontrol system for a fuel injection device of internal combustionengines, according to claim 3, wherein said monostable multivibratorelement included in the trigger pulse generating means is a one-shotmonostable multivibrator element and said multivibrator element includedin the fluidic control circuit is an OR-NOR monostable multivibratorelement.
 6. A control system for a fuel injection device of internalcombustion engines, according to claim 4, wherein said fluidic controlcircuit further includes a monostable multivibrator element foramplifying the output pulse of said bistable multivibrator element.
 7. Acontrol system for a fuel injection device of internal combustionengine, comprising trigger pulse generating means for generating atrigger pulse in synchronism with the rotation or an internal combustionengine, first variable circuit-length means by which the length of afluid passage can be varied according to the load on the engine, secondvariable circuit-length means by which the length of a fluid passage canbe varied according to the atmospheric pressure, and fluidic controlcircuit for generating a fluidic pulse of a variable width and avariable number in cooperation with said first and second variablecircuit-length means and said trigger pulse generating means, thetrigger pulses generated by said trigger pulse generating means beingapplied, one to said fluidic control circuit through said secondvariable circuit-length means and the other one to said fluidic controlcircuit and said first variable circuit-length means, whereby a fluidicpulse is generated by said fluidic control circuit, which is used forcontrolling the quantity of fuel supplied to said engine.